U.S. Pat. No. 4,533,372 to Jaime A. Valencia and Robert D. Denton discloses a method and apparatus for separating carbon dioxide and other acid gases from methane by treating a feedstream in a controlled freezing zone. Such treatment is referred to as the "CFZ Process". The CFZ Process provides for the solidification of carbon dioxide in a distillation tower in a controlled manner and permits the thermodynamic separation by distillation of a feedstream mixture containing carbon dioxide and methane in a single distillation column. The present invention can be used to provide improved heat transfer in the CFZ Process.